Unverified Commit 56495ac8 authored by Tommaso Tocci's avatar Tommaso Tocci
Browse files

Intercept realpath

parent 94a44560

ifs/include/preload/passthrough.hpp

+2 −0
Original line number Diff line number Diff line
@@ -70,6 +70,8 @@ extern void* libc_closedir; 


extern void* libc_chdir;



extern void* libc_realpath;



void init_passthrough_if_needed();



#endif //IFS_PASSTHROUGH_HPP

ifs/src/preload/intcp_functions.cpp

+23 −0
Original line number Diff line number Diff line
@@ -728,3 +728,26 @@ int chdir(const char* path){ 
    }

    return (reinterpret_cast<decltype(&chdir)>(libc_chdir))(path);

}



char *realpath(const char *path, char *resolved_path) {

    init_passthrough_if_needed();

    CTX->log()->trace("{}() called with path {}", __func__, path);

    std::string rel_path(path);

    if (CTX->relativize_path(rel_path)) {

        if(resolved_path != nullptr) {

            CTX->log()->error("{}() use of user level buffer not supported", __func__);

            errno = ENOTSUP;

            return nullptr;

        }

        auto absolute_path = CTX->mountdir() + rel_path;

        auto ret_ptr = static_cast<char*>(malloc(absolute_path.size() +  1));

        if(ret_ptr == nullptr){

            CTX->log()->error("{}() failed to allocate buffer for called with path {}", __func__, path);

            errno = ENOMEM;

            return nullptr;

        }

        strcpy(ret_ptr, absolute_path.c_str());

        return ret_ptr;

    }

    return (reinterpret_cast<decltype(&realpath)>(libc_realpath))(path, resolved_path);

}

ifs/src/preload/passthrough.cpp

+4 −0
Original line number Diff line number Diff line
@@ -75,6 +75,8 @@ void* libc_closedir; 


void* libc_chdir;



void* libc_realpath;





void init_passthrough_() {

    libc = dlopen("libc.so.6", RTLD_LAZY);
@@ -146,6 +148,8 @@ void init_passthrough_() { 


    libc_chdir = dlsym(libc, "chdir");



    libc_realpath = dlsym(libc, "realpath");



}



void init_passthrough_if_needed() {